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Secure messaging on a bockchain. Due to the fact you no longer have to trust a 3rd party. If you choose the Bitcoin blockchain then you can send your encrypted

Secure messaging on a bockchain. Due to the fact you no longer have to trust a 3rd party. If you choose the Bitcoin blockchain then you can send your encrypted data and no-one will know who decrypted it due to the P2P nature of the network. Every node receives every message. Example. AES encrypt your message with a key you both know. Add it to the message field of a bitcoin tranasction. The person at the other end decrypts any transaction they find with a message until they find one which does decrypt with that key. For more securtity you can hide the message in the content of the transaction. i.e. the public keys you pay to.

Frogolocalypse 9y ago
> i.e. the public keys you pay to. Or the public keys you pay from. You can break a txn into multiple components, each of which is formed as a function of a deterministic wallet. By having multiple change addresses you'd have more message space. > Every node receives every message. You could even send it with a very low mining fee, and theoretically the message would disappear. But it would require gaming of the system, because many nodes wouldn't pass-on txns that don't have a minimum txn fee. This functionality is one of the key reasons that blocksize space needs to be controlled on a block-chain.
jwalton 9y ago
> no-one will know who decrypted it > Every node receives every message. Neither one of these strike me as desirable characteristics of a secure messaging system. I can see the advantage in a third party not being able to tell who received a message, but in a perfect world as the sender I'd like to know that only my intended recipient received it, which is the opposite of what's going to happen with the block chain. Also, to encrypt with AES you need to pick a key length, and since your message is going to everyone in the world, you need to pick a key that is both impractical to break using today's technology, but using all future technology for as long as your secret remains relevant. If AES is ever broken, then all bets are off. If you have a chance to exchange keys of unlimited length ahead of time, then you could use a one time pad and message over the block chain. This would be secure, but then if you have a OTP, almost any message channel you pick is going to be secure. Someone else in this conversation recommended using newspaper ads.
- 1ba9115454 9y ago
  > no-one will know who decrypted it This is useful when you want to send a mesage but you don't want anyone to know who you were sending too. It's a form of obfuscation.

Frogolocalypse 9y ago

> i.e. the public keys you pay to. Or the public keys you pay from. You can break a txn into multiple components, each of which is formed as a function of a deterministic wallet. By having multiple change addresses you'd have more message space. > Every node receives every message. You could even send it with a very low mining fee, and theoretically the message would disappear. But it would require gaming of the system, because many nodes wouldn't pass-on txns that don't have a minimum txn fee. This functionality is one of the key reasons that blocksize space needs to be controlled on a block-chain.

jwalton 9y ago

> no-one will know who decrypted it > Every node receives every message. Neither one of these strike me as desirable characteristics of a secure messaging system. I can see the advantage in a third party not being able to tell who received a message, but in a perfect world as the sender I'd like to know that only my intended recipient received it, which is the opposite of what's going to happen with the block chain. Also, to encrypt with AES you need to pick a key length, and since your message is going to everyone in the world, you need to pick a key that is both impractical to break using today's technology, but using all future technology for as long as your secret remains relevant. If AES is ever broken, then all bets are off. If you have a chance to exchange keys of unlimited length ahead of time, then you could use a one time pad and message over the block chain. This would be secure, but then if you have a OTP, almost any message channel you pick is going to be secure. Someone else in this conversation recommended using newspaper ads.

1ba9115454 9y ago
> no-one will know who decrypted it This is useful when you want to send a mesage but you don't want anyone to know who you were sending too. It's a form of obfuscation.